How marine calcifiers record climate and environment in carbonate crystals (or, why and how do palaeoproxies work?)
About the Event:
The development of proxies for past climate using chemical and isotopic signatures recorded in the shells of marine organisms provides the context for understanding climate today. An expanding range of proxies have been proposed that are (variously) thought to reflect ocean temperature, pH, salinity, and oxygen content, among others. Most such proxies, typically extracted from the chemical signatures of marine calcifying organisms such as foraminifera, coccoliths or corals, are developed based on empirical correlations. My interest in trace element (crystal) chemistry of CaCO3 stems from a coffee time conversation with Harry Elderfield, some years ago, in which we pondered why Mg/Ca ratios in forams work as indicators of temperature, Here I will chart the progress since made using synchrotron X-ray spectroscopy at the nanometre length scale, alongside other recent experimental and computational techniques (such as quantum mechanical structure calculations), to understand the underlying reasons why and how foraminifera and other organisms are able to provide insights into past marine environments.
About the Speaker:
Simon Redfern is a mineralogist, trained as a crystallographer, who is interested in the linked between atomic scale structure and the physical and chemical properties of planetary materials, from Earth’s oceans to core. His work explores how minerals control and reflect Earth processes and he has worked in collaboration with a wide variety of Earth and environmental scientists, from climate scientists to volcanologists to palaeontologist to seismologists and even exoplanetary “geo” scientists. In all cases he is interested in how insights into nanometre scale features provide understanding of global processes. His work has extended to using insights from Nature to develop new materials in the context of materials design and manufacture. He obtained his bachelors and PhD degrees from the Department of Earth Sciences at the University of Cambridge before taking up his first job as Lecturer in Geochemical Spectroscopy jointly between the Departments of Geology and Chemistry at the University of Manchester. He returned to Cambridge after a short while and spent a quarter of a century there in various academic roles, before becoming Head of Department. He left Cambridge this summer to move to NTU and take up the post of President’s Chair in Earth Sciences here at ASE, alongside the role of Dean of Science in CoS.